The present invention relates to an air discharge pressure measuring device for measuring a discharge pressure of air that is fed by an air feeding device for an endoscope and discharged from an endoscope.
Conventionally, an air feeding device is used for feeding air into an endoscope. The air is fed by the air feeding device to, for example, a forceps channel of the endoscope. The air discharge from the endoscope is used for removing soil applied onto a cover glass of an observing optical system, for inflating human cavity so as to enable observation thereof easily, and the like.
Recently, a diagnosis method for discharging air toward a throat or a stomach and observing the condition of the portion at which the air struck has been developed. In order to apply such a diagnosis method precisely, the pressure of the air discharge from the endoscope is required to be adjusted accurately. Therefore, it is necessary to measure a discharge pressure of the air that is discharged from the endoscope and is to strike the human cavity.
It is therefore an object of the invention to provide an improved air discharging pressure measuring device for an endoscope with which the discharging pressure of the air discharged from an endoscope can be measured accurately and with stability.
For the above object, according to the present invention, there is provided a discharge pressure measuring device for an endoscope having an air supply tube to discharge the air inside a human cavity, which is provided with a discharge pressure measuring system that detects a discharge pressure of the air discharged from an outlet of the air supply tube.
Optionally, the discharge pressure measuring system may include a pressure sensor that outputs a voltage corresponding to a received pressure. In this case, the air discharge from the outlet of the air supply tube is to be directed to strike the pressure sensor.
When the pressure sensor is used, the discharge pressure measuring system can detect the discharge pressure based on the voltage output by the pressure sensor.
The outlet of the air supplying tube is fixed with respect to the endoscope so that the air is discharged to the pressure sensor under a predetermined stable condition.
Optionally, the discharge pressure measuring system may include a fixed pipe, which communicates with the air supplying tube. In this case, the air discharged from the outlet of the air supplying tube is directed, through the pipe, to a pressure sensing portion of the pressure sensor.
Further optionally, the pipe may be connected with the air supplying tube via a flexible air tube.
Further more, the air tube may connect a connectable end of the pipe and a distal end of the endoscope where the discharge port is provided to extend along a straight line.
In this case, it is preferable that the connectable end of the pipe is formed such that the air tube is not disconnected easily.
Optionally, the pressure sensing portion of the pressure sensor and the pipe are located at the same level in view of gravity, and the pressure sensing portion of the pressure sensor and a discharging end of the pipe face to each other.
In this case, it is preferable that a central axis of the pipe intersects a center of the pressure sensing portion of the pressure sensor.
Further, an area of the pressure sensing portion of the pressure sensor may be substantially equal to or greater than an area of the discharging end of the pipe.
Still optionally, the discharging pressure measuring system is constituted such that a distance between the discharging end of the pipe and the pressure sensing portion of the pressure sensor is changeable.
In this case, it is preferable that graduations are provided to the pipe for measuring the distance between the discharging end of the pipe and the pressure sensing portion of the pressure sensor is changeable.
Further optionally, the discharge pressure measuring device may be provided with a pipe supporting member. The pipe supporting member may be formed with a through hole in which the pipe is fitted, and the pipe is fixed with respect to the pipe supporting member by means of a screw.
The discharge pressure measuring device may have a body which includes a metal plate, the pipe supporting member and a lower base.
Further, a chamber for accommodating the pressure sensor may be formed by the metal plate and a sensor fixing member. The pressure sensor may be fixed to the chamber by an O-ring.
In this case, the sensor fixing member is formed to have a hole at a portion where the discharged air passes, the discharged air passed through the hole being directed to the pressure sensing portion of the pressure sensor. The hole may be sufficiently greater than the discharging end of the pipe and the pressure sensing portion of the pressure sensor.
The metal plate may be formed to have an L-shaped cross section, and the metal plate may be fixed onto the lower base such that one of two straight portion of the L-shaped cross section forms an upper surface of the body.
In this case, a circuit board mounting a circuitry for detecting the voltage representing the discharge pressure may be fixed on the metal plate by means of screws.
According to another aspect of the invention, there is provided a discharge pressure measuring device, which is provided with:
a discharge pressure measuring member that measures a discharge pressure of the air discharged from a discharging end of an air supplying tube provided to an endoscope;
a communication member that directs the air discharged by the discharging end to a pressure sensing portion of the discharging pressure measuring member;
a circuit board mounting a circuitry for obtaining a voltage representing a true discharge pressure based on a voltage output by the discharge pressure measuring member; and
a casing for accommodating the discharge pressure measuring member, the communication member and the circuit board. In this case, the communication member is mounted onto the casing such that a positional relationship with respect to the pressure sensing portion is changeable.
Optionally, the communication member may include an air tube and a pipe. An end of the air tube may be connected to a distal end of the endoscope, the other end of the air tube may be connected to an end of the pipe, and the other end portion of the pipe may be mounted on the casing such that a distance to the pressure sensing portion is changeable.
Further optionally, gradations may be provided on the pipe for measuring the distance between the other end of the pipe and the pressure sensing portion.
According to a further aspect of the invention, there is provided a discharge pressure measuring device for an endoscope, which is provided with:
a discharge pressure measuring system that measures a discharge pressure of air which is discharged from an air supplying tube provided to an endoscope with a pressure sensor;
a peak hold processing system that holds a peak value of a voltage output by the pressure sensor, the voltage corresponding to a pressure of the discharged air;
a reset system that resets the voltage held by the peak hold processing system;
a short circuit preventing system that prevents short-circuiting of an electric circuitry when the voltage held by the peak hold processing system is reset.
Optionally, the peak hold circuit may include: an input operational amplifier to which the voltage output by the pressure sensor is supplied; an output operational amplifier from which a voltage is output; at least two resistors which are serially connected; a diode; a condenser; and a transistor. In this case, the short circuit preventing system should include an arrangement such that the at least two resistors being connected with the diode in parallel. The condenser is connected between a cathode of the diode and the ground, a collector of the transistor is connected with a portion where the at least two resistors are connected, and an emitter of the transistor is connected to the ground.
Optionally, the at least two resistors may include a first resistor and a second resistor, the first resistor being located on a condenser side, a resistance of the first resistor being much smaller than that of the second resistor.
Further optionally, when the voltage representing the discharge pressure is input to the input operational amplifier, the peak hold circuit accumulates electric charges in the condenser via the diode; and if the voltage input to the input operational amplifier is equal to or less than the maximum voltage, the maximum voltage is applied to the output operational amplifier.
In this case, electric charges, which corresponds to the maximum voltage, accumulated by the condenser are discharged as the input operational amplifier is connected to the ground via the first condenser and the transistor when the reset signal is transmitted to the base of the transistor.
Optionally, the voltage output by the pressure sensor may be amplified before transmitted to the peak hold circuit.
It is preferable that the amplified voltage is transmitted to an operation system, through the peak hold circuit, and directly.
In this case, the discharge pressure measuring system detects the discharge pressure based on a difference between the maximum voltage transmitted to the operation system by the peak hold circuit, and a reference voltage which is input directly to the operation system when the air is not discharged.